Messenger directs me to another account NOT MINE!!!!!

My son does not have a FB account but he had a Messenger account installed on his mobile phone (Android). Lately he uninstalled it due to that he had a phone issue and when he tried to reinstalling it, after he inputs his phone number and inputs the code that FB sends him via SMS , the application asks him if he is someone else...”Are you Ni.. Ca..?” and there is a tab to press “Continue as Ni.. Ca.. “ or there is another tab which says “This isn’t my account”. When he press “This isn’t my account” he gets a window with “Are you sure this isn’t your account” and a tab “I’m sure”, when he press on this tab he gets the message “You have been temporarily blocked from performing this action”. Can anyone help please, I cleared the cache, the memory, reinstalled, factory reset phone, checked everything but I cannot get it working!! Thanks